How polling has changed since the 2016 election

Democratic Congressional candidates now hold a nine-point advantage over Republicans, according to the latest poll from the PBS NewsHour, NPR and Marist. But can polls be trusted? In 2016, polls in key states showed Hillary Clinton winning handily. Donald Trump won all three. Judy Woodruff discusses with NPR’s Domenico Montanaro and Patrick Murray of the Monmouth University Polling Institute.

PBS NewsHour